1. Field of the Disclosure
The present disclosure relates generally to toner cartridges and developer units used in electrophotographic imaging devices such as a printer or multifunction device having printing capability, and in particular shutters used to open and close toner ports on such toner cartridges and developer units.
2. Description of the Related Art
In toner cartridge design it is now common practice to separate the longer lived components from those having a shorter life. This has led to having the longer lived developing components such as the developer roll, toner adder rolls, doctor blades, the foregoing are also referred to as a developing unit, photoconductive drums, cleaning and charge rollers and a waste bin to be in separate assemblies from the toner cartridge. The toner supply, which is consumed relatively quickly in comparison to the previously described components, is provided in a reservoir in a separate toner cartridge that mates with the developer unit. The toner cartridge has a reduced number of components and is often referred to as a toner bottle even though it is more than a mere bottle for holding toner. Because both the developer unit and toner cartridge are each separable and removable from the imaging apparatus, both use shutter assemblies to open and close their respective toner entry port and toner exit port.
To deliver the toner from the toner cartridge to the developer unit, an auger in the toner cartridge may be used to feed toner from the toner cartridge via an exit port on the toner cartridge into an entry port on the developer unit and into a second auger that disperse the toner within the developer unit. As the toner is drawn out of the cartridge unit, it is augured through a shutter. The shutter in one position seals the exit port of the toner cartridge when it is not inserted in the imaging apparatus. Another shutter may be used for sealing the entry port of the developer unit when the toner cartridge has been removed.
The shutters in such shutter assemblies are rotatably mounted in the housings of the toner cartridge and the developer unit and are generally tapered or conical. This mounting requires that the spacing between the shutter and the housing be sealed in order to prevent a toner leak path from occurring between the shutter and the housing. Prior seals have been made from foam materials that are adhesively wrapped around the exterior of the shutter or rubber O-rings were used.
One problem with the traditional application of foam seals or O-rings is that it is difficult to have low frictional force between the shutter and the housing while maintaining proper sealing performance. Additionally, in some cases there are space constraints between the shutter and housing making it difficult to insert the shutter having a foam seal into the housing. The use of wrapped foam seals and O-ring seals result in high rotational frictional force during actuation of the shutter for opening and closing the toner port. This high frictional force must be overcome by a large force applied to the toner cartridge supplied by the shutter operator such as a plunger on a door of the imaging apparatus or by an arbor spring on the developer unit. If not, this will lead to risk of the shutter not fully opening which will impact the rate at which toner can be delivered or not fully closing which will increase the risk of toner leakage.
Another problem with the wrapped foam application is it is difficult to wrap a foam seal around a conically shaped shutter while aligning the mating joints and aligning the seal openings with the port openings in the shutter. This process can result in excessive rotational frictional force, foam misalignment and toner leakage.
To provide a seal for a supply item having a high effective sealing force without a high rotation frictional force would be advantageous. It would be a further advantage to have such a seal to prevent toner escaping from the supply item, such as a toner cartridge or developer unit, during shipping, storage, and when removed from the imaging apparatus. It would be a further advantage to be able to provide a shutter that will open fully to ensure a high rate of toner delivery.